Boosting near-infrared absorption properties enabled by oxygen vacancy engineering within tungsten trioxide

Tungsten-based semiconductor nanomaterials have great potential for developing energy-saving windows as a consequence of excellent shielding performance in the near-infrared (NIR) region. The performance of such nanomaterials is profoundly influenced by the the oxygen vacancies (OVs). However, the relationship between NIR absorption properties and OVs concentration has been rarely explored. In this work, the WO3-x nanosheets capable of various OVs concentration were successfully synthesized via a simple solvothermal approach, and we have carefully investigated their optical properties. Particularly, we found that the WO3-x-Pr nanosheets showed the strongest UV and NIR absorption, with the transmittance in visible region is up to 60%. Furthermore, this material is capable of the lowest temperature gap (about 11.4 °C). This work manifests that the optical performance of the tungsten (W)-based semiconductor nanomaterials is highly depended by the OVs concentration.